1. Field of the Invention
The present invention relates to a positioning system of wireless terminal, and more particularly, a wireless terminal using at least two positioning method, a computer program products for a wireless terminal and a method for transmitting information from a wireless terminal.
2. Related Art
Terminals having wireless communication functions are called wireless terminals. Mobile phones, mobile terminals and portable computers are among the known wireless terminals. Also known are positioning systems for pointing the locations of wireless terminals. For example, there are known positioning systems which use satellites and positioning systems which use ground base stations, e.g., telephone stations. Specifically, the Global Positioning System and the Code Division Multiple Access Communication System are available for use. In these positioning systems, each wireless terminal fetches data from stations of a positioning system, and has its location pointed based on the fetched data. For one example, a wireless terminal fetches search data from GPS satellites as stations of a GPS system. For another example, a wireless terminal fetches search data from CDMA base stations as stations of a mobile phone system.
For example, a mobile phone is operated by the user to commence the positioning operation. The mobile phone searches for CDMA base stations thereby to fetch CDMA base station data pertinent to the searched stations. The mobile phone sends the CDMA base station data to a position data server and requests the server to release assistant data useful for the mobile phone to search for GPS satellites.
The position data server receives the CDMA base station data from the mobile phone. The position data server determines the approximate location of the mobile phone based on the received CDMA base station data, computes assistant data useful for the mobile phone to search for GPS satellites, and sends the computed assistant data to the mobile phone. The mobile phone receives the assistant data, searches for GPS satellites based on the assistant data thereby to fetch GPS satellite data, and sends the fetched data to the position data server and requests the server to release a positioning result.
The position data server receives the GPS satellite data from the mobile phone. The position data server points the location of the mobile phone based on the GPS satellite data provided by the mobile phone and the CDMA base station data which has already been provided, and sends a positioning result indicative of the pointed location to the mobile phone.
This positioning system enables the mobile phone to search for GPS satellites based on assistant data provided by the position data server, and therefore it is possible for the whole system to reduce the time needed for positioning. The location of mobile phone is pointed by the position data server, instead of being done by the mobile phone itself, and therefore the mobile phone can lighten the duties and reduce the power consumption.
The mobile phone occasionally has to expend a long time in searching GPS satellite and a long time in fetching GPS satellite data due to adverse circumstances. In such a case of expending a long time for fetching GPS satellite data, the mobile phone is liable to fail the fetching of proper GPS satellite data. As a result, the conventional positioning system is deficient in utility in that the mobile phone user is subjected to long time waiting, but still get inaccurate positioning results.